The present invention relates to a process for continuously producing metal-laminated base materials for printed circuit boards.
Metal-laminated base materials for printed circuit boards are generally produced discontinuously when cut-to-size laminated material, provided with thermosetting resin, and metal foils are pressed in multiple-daylight presses. Such a process is expensive and supplies base materials of a quality which varies within the individual board. There has therefore long been a desire for a continuous process.
A step towards continuity is shown in British Patent Application No. 2,108,427 which describes a process in which intermittent pressing is carried out in a press having two heated plates, in such a way that a sheet of fabric and a copper foil which are introduced into the press are each stationary during the pressing operation and the press product is ejected periodically. The product of this process therefore consists of individual portions, the dimensions of which are limited by those of the heated plates and which are joined to one another by non-pressed, that is to say unusable, portions. Even here, the quality varies within the individual board, and when the consumer demands a uniform quality this results in large quantities of rejects.